Development of an on-line scintillation flow-cell detection system with pulse shape discrimination for quantification of actinides

A flow-cell detection system was developed utilizing pulse shape discrimination as a means of reducing the beta (gamma-ray) background when quantifying alpha emitters. Flow-cells consisting of 63-90 /spl mu/m particles of CaF/sub 2/:Eu, scintillating glass (GS-20), and BaF/sub 2/ were each packed into translucent Teflon tubing. CaF/sub 2/:Eu and GS-20 exhibited only marginal pulse shape resolution, achieving figures of merit, (FOM) of 0.46 and 0.27, respectively. BaF/sub 2/ exhibited reasonable pulse shape resolution, FOM=0.75. Unfortunately, the presence of intrinsic alpha emitters in CaF/sub 2/:Eu and BaF/sub 2/ resulted in an elevated background count rate in the alpha window. Coupled with a detection efficiency of /spl sim/50% for /sup 233/U (E/sub /spl alpha//=4.8 MeV) alpha particles, minimum detectable activities at the optimal pulse shape time discriminator setting were 0.6 Bq for CaFa/sub 2/:Eu and BaF/sub 2/ and 1.1 Bq for GS-20.<
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